Shallow donors in GaN—The binding energy and the electron effective mass

Meyer, B. K.; Volm, D.; Graber, A.; Alt, H. Ch.; Detchprohm, Theeradetch; Amano, Akio; Akasaki, Isamu

doi:10.1016/0038-1098(95)00337-1

Cited by 165 publications

(84 citation statements)

References 7 publications

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“…The 17 Although our fitted E D is in excellent agreement, it should not be taken as a verification of E D0 or ␣; much more work on many other samples will be necessary to establish these two parameters accurately. In fact, a value of E D0 ϭ35 meV for residual donors ͑perhaps Si͒ has also been suggested.…”

Section: ͑8͒mentioning

confidence: 71%

Degenerate layer at GaN/sapphire interface: Influence on Hall-effect measurements

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Molnar

1997

Applied Physics Letters

353

207

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Temperature-dependent Hall-effect measurements in hydride vapor phase epitaxial GaN grown on sapphire can be well fitted over the temperature range 10–400 K by assuming a thin, degenerate n-type region at the GaN/sapphire interface. This degenerate interfacial region dominates the electrical properties below 30 K, but also significantly affects those properties even at 400 K, and can cause a second, deeper donor to falsely appear in the analysis. However, by using a two-layer Hall model, the bulk mobility and carrier concentration can be accurately ascertained.

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Section: ͑8͒mentioning

confidence: 71%

Degenerate layer at GaN/sapphire interface: Influence on Hall-effect measurements

Look

Molnar

1997

Applied Physics Letters

353

207

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“…39 Moreover, the shallower-donor energy levels associated with higher n e values can be explained by the screening effect. 39,40 Therefore, the estimated value of the energy level of V O s at the shallow-donor state through analysis of P-F conduction is highly reliable. Because the value of E C − E D is higher than the value of k B T, the field-enhanced thermal excitation of free electrons (that is, P-F conduction) is possible.…”

Section: Resultsmentioning

confidence: 99%

Structural-relaxation-driven electron doping of amorphous oxide semiconductors by increasing the concentration of oxygen vacancies in shallow-donor states

et al. 2016

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The electronic states of oxygen vacancies (V O s) in amorphous oxide semiconductors are shallow donors, deep donors or electron traps; these are determined by the local atomic structure. Because the amorphous phase is metastable compared with the crystalline phase, the degree of structural disorder is likely to decrease, which is referred to as structural relaxation (SR). Thus SR can affect the V O electronic state by changing the local atomic conditions. In this study, we demonstrated that electron doping is possible through the SR of amorphous oxides without redox reactions using a novel device structure that prevents extrinsic reactions with electrodes and ambient atmosphere during annealing. The concentration of V O s in the shallow-donor state in amorphous In-Ga-Zn-O (a-IGZO) increases from~10 16 to~10 19 cm − 3 with increasing annealing temperatures between 300 and 450°C. The SR-driven doping effect is strongly dependent on the annealing temperature but not on the annealing time. The Arrhenius activation energy of the SR-driven doping effect is 1.76 eV, which is similar to the bonding energies in a-IGZO. Our findings suggest that the free volume in a-IGZO decreases during SR, and the V O s in either deep-donor or electrontrap states are consequently transformed into shallow-donor states. NPG Asia Materials (2016) 8, e250; doi:10.1038/am.2016.11; published online 25 March 2016 INTRODUCTION Amorphous metal oxides, such as amorphous indium gallium zinc oxide (a-IGZO), have become mainstream materials for large-area and flexible electronics because the long-range structural disorder enhances the uniformity of the electrical properties and mechanical flexibility compared with crystalline metal oxides. 1-5 A notable characteristic of amorphous oxides, relative to their crystalline counterparts, is that these materials contain structural disorder-related defects (for example, free volume) in addition to non-stoichiometric defects (for example, oxygen vacancies), which significantly affect the corresponding electrical properties. 3,[6][7][8] Moreover, the degree of structural disorder in amorphous metal oxides is always likely to decrease to form more stable structures because internal atomic rearrangement occurs even below the glass transition temperature (T g ). This process is known as structural relaxation (SR) 9-11 and results in continuous changes in the electrical properties. Thus understanding the effects of SR on the electrical properties of amorphous oxides is important for applications in future electronics.In addition to uniformity and flexibility, amorphous metal oxides exhibit tunable electrical conductivity through redox reaction control

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“…12 For ZnO we can approximate ␣ as ͓( ZnO / GaN )(m GaN * /m ZnO * )͔␣ GaN giving a value ␣Ӎ1.2ϫ10 Ϫ5 meV cm. One sees that the screening in ZnO is somewhat weaker than that in GaN.…”

Section: ͑1͒mentioning

confidence: 99%

Combined effects of screening and band gap renormalization on the energy of optical transitions in ZnO and GaN

Reynolds¹,

Jogai²

2000

Journal of Applied Physics

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The energy positions of the optical transitions in both GaN and ZnO were investigated when the samples were excited simultaneously with a HeCd laser and an Ar ϩ ion laser. The increased number of free electrons excited by the Ar ϩ ion laser will effectively screen both the free exciton and bound exciton transitions, resulting in a blueshift. The increased number of free electrons also produces many-body effects, which lead to a reduction of the band gap energy and thus a redshift. The resultant of screening and renormalization results in a redshift of the optical transitions in ZnO but a nearly vanishing shift in GaN.

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Shallow donors in GaN—The binding energy and the electron effective mass

Cited by 165 publications

References 7 publications

Degenerate layer at GaN/sapphire interface: Influence on Hall-effect measurements

Degenerate layer at GaN/sapphire interface: Influence on Hall-effect measurements

Structural-relaxation-driven electron doping of amorphous oxide semiconductors by increasing the concentration of oxygen vacancies in shallow-donor states

Combined effects of screening and band gap renormalization on the energy of optical transitions in ZnO and GaN

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